(1) Field of the Invention
This invention relates to an optical disc recording apparatus, a computer-readable recording medium recording a file management program, and an optical disc.
(2) Description of the Prior Art
Recently, recording mediums such as magneto optical discs (MO) have been widely used for recording data to be read by computers. Currently, practical uses of DVD (Digital Versatile Disc)-RAM discs are waited for due to general expectation that DVD-RAMs will become a main recording medium of the next generation.
In conventional MOs, like HD (Hard Disc) or FD (Flexible Disc), the minimum unit in accessing data on discs is xe2x80x9csectorxe2x80x9d having several kilobytes. Each file is recorded in one or more sectors.
Reading and writing of files from/onto discs are executed by computers as functions of a file system which is a part of operating systems (OS). A file system is defined, for example, in ISO/IEC13346.
According to a conventional technique, for example, when recording a file of 200 KB onto a recording medium with 2 KB-sectors, computers must find 100 unassigned sectors on the recording medium. The 100 unassigned sectors need not be physically consecutive. For example, when four separate groups respectively having 30, 30, 30, and 10 unassigned sectors are found on the recording medium, the file is divided into the four groups of sectors. Each part of the file recorded in each group of sectors, namely each group of consecutive sectors, is called xe2x80x9cextentxe2x80x9d.
In such a conventional technique, files can be divided and recorded into a plurality of extents. This provides a merit that all the sectors on a recording medium can be used efficiently even after recording and deleting of files on the medium are repeated a number of times.
However, conventional recording mediums and file systems have a problem that uninterrupted reproduction of audio/video data (hereinafter referred to as AV data) recorded on the recording mediums cannot be ensured.
More specifically, when recording and deleting of files on a recording medium are repeated several times, the AV data may not be recorded in consecutive sectors. The AV data may be divided and recorded into a plurality of extents, as described above. When this happens, the reproduction apparatus cannot achieve uninterrupted reproduction of the AV data due to a seek operation of an optical pickup that occurs as the optical pickup moves between the plurality of extents.
For example, when a seek occurs between a sector at the innermost periphery and a sector at the outermost periphery of a disc, the seek time amounts to several-hundred milliseconds. In case of moving images, such a seek of several-hundred milliseconds interrupts reproduction since reproducing 30 frames per second is required for reproduction of moving images.
As described above, uninterrupted reproduction may not be ensured by conventional file systems. This is especially a serious problem for mass storages such as DVD-RAM on which, like VTR, a plurality of pieces of AV data (e.g., TV programs) can be recorded, edited, and deleted.
Here, it should be reminded that recording mediums can also record computer data, as well as AV data. Accordingly, particular attention should be paid on how to efficiently store both types of data on a disc.
It is therefore an object of the present invention to provide an optical disc recording apparatus, a computer-readable recording medium recording a file management program, and an optical disc which ensure uninterrupted reproduction of AV data and record various types of data including AV data together and efficiently.
The above object is achieved by an optical disc recording apparatus for recording a video object on an optical disc, where a recording area of the optical disc is divided into a plurality of zones which each include a plurality of adjacent tracks, and includes sector information showing data assignment for sectors on the optical disc, the optical disc recording apparatus including: a reading unit for reading the sector information from the optical disc; a recording unit for recording the video object onto the optical disc; and a control unit for controlling the reading unit and the recording unit, where the control unit: detects at least one series of consecutive unassigned sectors on the optical disc by referring to the read sector information, each series having a total size greater than a minimum size and being located within a single zone, the minimum size corresponding to a data amount that ensures uninterrupted reproduction of the video object; and controls the recording unit to record the video object into the detected series.
With the above construction, the video object is recorded in a series of consecutive unassigned sectors with the total size greater than a predetermined size, the series without including a zone boundary. This is achieved by searching of such a series of consecutive unassigned sectors prior to the recording of the video object onto the optical disc. The predetermined size is set so that the uninterrupted reproduction is ensured in any types of reproduction apparatuses. As a result, the video object recorded by the present optical disc recording apparatus is reproduced by any types of reproduction apparatuses without gaps in the reproduced video and audio images (without missing frames). Also, the record area is divided into a plurality of zone areas to realize rotation control called Z-CLV (Zone-Constant Linear Velocity) during recording and reproduction. By doing so, a qualified recording efficience is achieved without sacrificing the recording density of the outermost periphery of the optical disc. Also, the uninterrupted reproduction is ensured since the video object does not outstep the zone boundary.
In the above optical disc recording apparatus, the recording area of the optical disc may be divided into a plurality of 2 KB sectors, with each set of 16 consecutive sectors forming one ECC block, the video object is composed of a plurality of packs, each pack having a size of 2 KB, the minimum size is the number of ECC blocks which is represented as xe2x80x9cN_eccxe2x80x9d in the following formula: N_ecc=Vo*Tj/((16*8*2048)*(1xe2x88x92Vo/Vr)), where xe2x80x9cTjxe2x80x9d represents a maximum jump time of an optical pickup of a reproduction apparatus, xe2x80x9cVrxe2x80x9d represents an input transfer rate (Mbps) of a track buffer of the reproduction apparatus, and xe2x80x9cVoxe2x80x9d represents an effective output transfer rate (Mbps) of the track buffer.
With the above construction, the predetermined size for ensuring the uninterrupted reproduction can be obtained in case defective sectors are not included in the series of consecutive unassigned sectors.
In the above optical disc recording apparatus, the recording area of the optical disc is divided into a plurality of 2 KB sectors, with each set of 16 consecutive sectors forming one ECC block, the video object is composed of a plurality of packs, each pack having a size of 2 KB, the minimum size is the number of ECC blocks which is represented as xe2x80x9cN_eccxe2x80x9d in the following formula: N_ecc=dN_ecc+Vo*Tj/((16*8*2048)*(1xe2x88x92Vo/Vr)), where dN_ecc is a number of ECC blocks, in a series of consecutive unassigned sectors, that include defective sectors, xe2x80x9cTjxe2x80x9d represents a maximum jump time of an optical pickup of an reproduction apparatus, xe2x80x9cVrxe2x80x9d represents an input transfer rate (Mbps) of a track buffer of the reproduction apparatus, and xe2x80x9cVoxe2x80x9d represents an effective output transfer rate (Mbps) of the track buffer.
With the above construction, the predetermined size for ensuring the uninterrupted reproduction can be obtained in case defective sectors are included in the series of consecutive unassigned sectors.
In the above optical disc recording apparatus, the effective transfer rate Vo may be found according to the following formula:
Vo=(N_pack*2048*8)*(27 M/(SCR_first_nextxe2x88x92SCR_first_current) 
where N_pack is the total number of packs included in the video object that should be recorded in N_ecc ECC blocks, SCR_first_current is a time (in 1/(27 mega) seconds) at which the track buffer of the reproduction apparatus should output the first pack of the video object, and SCR_first_next is a time (in 1/(27 mega) seconds) at which the track buffer of the reproduction apparatus should output the first pack of the following video object.
With the above construction, it is possible to obtain, based on the effective output transfer rate, the predetermined size for video objects with a variable bit rate. This achieves, for example, an efficient use of optical disc having a small amount of unassigned areas.
In the above optical disc recording apparatus, the control unit may generate management information showing areas of the optical disc where the video object has been recorded by the recording unit and controls the recording unit to record the generated management information onto the optical disc, and when the reading unit reads out management information from the optical disc, the control unit refers to the read management information as well as the sector information to detect the series.
With the above construction in which the management information is recorded on the optical disc, it is possible to detect unassigned areas at high speed and without difficulty.
The above object is also achieved by a computer-readable recording medium prestoring a file management program for recording a video object onto an optical disc, the file management program being to be run by a computer which includes: a reading unit for reading data from an optical disc; and a recording unit for recording data onto the optical disc, where a recording area of the optical disc is divided into a plurality of zones which each include a plurality of adjacent tracks, and includes sector information showing data assignment for sectors on the optical disc, the file management program including the following steps to be executed by the computer: a reading step for reading the sector information from the optical disc; a detecting step for detecting at least one series of consecutive unassigned sectors on the optical disc by referring to the read sector information, each series having a total size greater than a minimum size and being located within a single zone, the minimum size corresponding to a data amount that ensures uninterrupted reproduction of the video object; and a recording step for recording the video object into the detected series.
With the above construction in which the computer runs the file management program, it is possible to record the video object into the series of consecutive unassigned sectors which is larger than a predetermined size. This ensures the uninterrupted reproduction of the video object.
The above object is also achieved by a computer-readable optical disc including a data recording area, where the data recording area is divided into a plurality of zones which each include a plurality of adjacent tracks, and the data recording area includes: sector information showing data assignment for sectors on the optical disc; and management information showing areas of the optical disc where a video object has been recorded and are located within a single zone.
The above object is also achieved by a computer-readable optical disc including a data recording area, where the data recording area is divided into a plurality of blocks which each include a plurality of consecutive sectors, and the data recording area includes: an area for recording sector information showing data assignment for sectors on the optical disc; and a management area for recording block information showing data assignment for blocks on the optical disc.
With the above construction, it is possible to record data in units of sectors or blocks. Each block includes a plurality of consecutive sectors. Accordingly, even if one file is divided and recorded into a plurality of extents, the size of the extent is larger than the size of the block at the minimum. As a result, it is possible to ensure the uninterrupted reproduction of the video data recorded on the present optical disc by preventing interruptions which are cased by occurrences of seek operations in the reproduction apparatus. Furthermore, data management in units of sectors and blocks are performed together depending on the types of data. This achieves efficient use of the recording area of the optical disc.
In the above computer-readable optical disc, when the block information shows that blocks have been assigned to data that is mainly composed of video data, the sector information may show that all sectors in the assigned blocks have been assigned.
With the above construction, even if data is recorded by a conventional file system which uses a file management system managing data in units of sectors, the blocks assigned to video data are not overwritten by another data. Such a computer-readable optical disc is suitable for uninterrupted reproduction.
In the above computer-readable optical disc, a block size represented as xe2x80x9cLxe2x80x9d may satisfy the following formula:
L greater than T*Vin*Vout/xe2x80x2(Vinxe2x88x92Vout), 
where xe2x80x9cLxe2x80x9d (bits) represents the block size, xe2x80x9cTxe2x80x9d (seconds) represents a seek time of a reproduction apparatus, xe2x80x9cVinxe2x80x9d represents an input transfer rate (Mbps) of a buffer of the reproduction apparatus, and xe2x80x9cVoutxe2x80x9d represents an effective output transfer rate (Mbps) of the buffer.
In the above computer-readable optical disc, when the block information shows that blocks have been assigned to data that is not video data, the sector information may show that among sectors in the assigned blocks, only sectors recording the data have been assigned.
With the above construction, it is possible to record data other than video data (non-video) into unassigned sectors in blocks which have been assigned to non-video data. With this arrangement, even if video data and other types of data are recorded in mixture, the uninterrupted reproduction is ensured, and both of video and other types of data are stored efficiently.
In the above computer-readable optical disc, the data recording area may be divided into a plurality of zones which each include a plurality of adjacent tracks, and each of the plurality of blocks is included in any one of the plurality of zones.
With the above construction, the record area is divided into a plurality of zone areas to realize Z-CLV. By doing so, a qualified recording efficiency is achieved without sacrificing the recording density of the outermost periphery of the optical disc. Also, the uninterrupted reproduction is ensured since the video object does not outstep the zone boundary.
In the above computer-readable optical disc, blocks in each zone may have the same size except a block that is adjacent to a zone boundary, and the block that is adjacent to the zone boundary has a size being equal to or larger than the size of the other blocks.
With the above construction, it is possible to use the data recording area efficiently since one block in each zone has a size larger than the common size of the other blocks.
In the above computer-readable optical disc, the block that is adjacent to the zone boundary may include a sector having a maximum sector address in the current zone, and the management area includes a maximum block length table which shows, for each zone, sizes of blocks which each include the sector having the maximum sector address in a zone.
With the above construction, it is possible to manage variable-length blocks around the zone boundary without difficulty.
In the above computer-readable optical disc, an error correction code may be attached to every predetermined number of consecutive sectors, and each block may be composed of an integral multiple of the predetermined number of consecutive sectors.
With the above construction, it is possible for the recording/reproducing apparatus to record and reproduce continuously without generating overhead since each block is composed of an integral multiple of the predetermined number of consecutive sectors.
The above object is also achieved by an optical disc recording apparatus for recording data onto an optical disc which includes: a data recording area divided into a plurality of sectors; and a management area for recording sector information showing data assignment for sectors on the optical disc and block information showing data assignment for blocks on the optical disc, the optical disc recording apparatus including: a reading unit for reading the block information and the sector information from the optical disc; a judging unit for judging a type of the data to record or delete the data, the type being classified into a first type and a second type; a first specifying unit for, when the judging unit judges that the data is the first type, specifying, based on the read block information, either of: unassigned blocks in which the data is to be recorded: and blocks in which the data has already been recorded; a second specifying unit for, when the judging unit judges that the data is the second type, specifying, based on the read sector information, either of: unassigned sectors in which the data is to be recorded; and sectors in which the data has been recorded; a data updating unit for either of recording and deleting first-type data into/from the blocks specified by the first specifying unit and for either of recording and deleting second-type data into/from the sectors specified by the second specifying unit; and an assignment updating unit for updating at least one of the sector information and the block information in accordance with operations of the data updating unit.
With the above construction, it is possible to record data in units of sectors or blocks. Each block includes a plurality of consecutive sectors. Accordingly, even if one file is divided and recorded into a plurality of extents, the size of the extent is larger than the size of the block at the minimum. As a result, it is possible to ensure the uninterrupted reproduction of the video data recorded on the present optical disc by preventing interruptions which are cased by occurrences of seek operations in the reproduction apparatus. Furthermore, data management in units of sectors and blocks are performed together depending on the types of data. This achieves efficient use of the recording area of the optical disc.
In the above optical disc recording apparatus, the assignment updating unit may include: a block information updating unit for, when the first specifying unit specifies unassigned blocks, updating the block information by changing indication of the specified blocks from xe2x80x9cunassignedxe2x80x9d to xe2x80x9cassignedxe2x80x9d; and a sector information updating unit for, when the block information updating unit updates the block information by changing indication of the specified blocks from xe2x80x9cunassignedxe2x80x9d to xe2x80x9cassigned,xe2x80x9d updating the sector information by changing indication of all sectors included in the specified blocks from xe2x80x9cunassignedxe2x80x9d to xe2x80x9cassigned.xe2x80x9d
With the above construction, even if data is recorded by a conventional file system which uses a file management system managing data in units of sectors, the blocks assigned to video data are not overwritten by another data. Such a computer-readable optical disc is suitable for uninterrupted reproduction.
In the above optical disc recording apparatus, the block information updating unit, when the first specifying unit specifies blocks which are assigned to a piece of first-type data to be deleted, updates the block information by changing indication of the specified blocks from xe2x80x9cassignedxe2x80x9d to xe2x80x9cunassigned,xe2x80x9d and the sector information updating unit, when the block information updating unit updates the block information by changing indication of the specified blocks from xe2x80x9cassignedxe2x80x9d to xe2x80x9cunassigned,xe2x80x9d updates the sector information by changing indication of all sectors included in the specified blocks from xe2x80x9cassignedxe2x80x9d to xe2x80x9cunassigned.xe2x80x9d
With the above construction, it is possible to use the data recording area efficiently by recording the first-type data and the second-type data in mixture since all the sectors in a block are released when the first-type data is deleted.
In the above optical disc recording apparatus, the block information may show whether each block is: (1) unassigned data; (2) assigned first-type data which is mainly composed of video data; or (3) assigned second-type data which is mainly composed of data other than the first-type data, where the assignment updating unit includes: a first updating unit for updating the block information; and a second updating unit for updating the sector information, where the first updating unit, when the second updating unit updates the sector information by changing indication of any sectors included in unassigned blocks to xe2x80x9cassigned,xe2x80x9d updates the block information by changing indication of the unassigned blocks from xe2x80x9cunassignedxe2x80x9d to xe2x80x9csecond-type data assigned,xe2x80x9d and the second updating unit, when the first updating unit updates the block information by changing indication of blocks from xe2x80x9cunassignedxe2x80x9d to xe2x80x9cfirst-type data assigned,xe2x80x9d updates the sector information by changing indication of all sectors included in the blocks to xe2x80x9cassigned.xe2x80x9d
With the above construction, it is possible to-manage the data recording area without difficulty by recording the first-type data and the second-type data in mixture.
The above object is also achieved by a computer-readable recording medium prestoring a file management program for recording data onto an optical disc which includes: a data recording area divided into a plurality of sectors; and a management area for recording sector information showing data assignment for sectors on the optical disc and block information showing data assignment for blocks on the optical disc, the file management program including the following steps to be executed by the computer: a reading step for reading the block information and the sector information from the optical disc; a judging step for judging a type of the data to record or delete the data, the type being classified into a first type and a second type; a first specifying step for, when in the judging step it is judged that the data is the first type, specifying, based on the read block information, either of: unassigned blocks in which the data is to be recorded: and blocks in which the data has already been recorded; a second specifying step for, when in the judging step it is judged that the data is the second type, specifying, based on the read sector information, either of: unassigned sectors in which the data is to be recorded; and sectors in which the data has been recorded; a data updating step for either of recording and deleting first-type data into/from the blocks specified by the first specifying unit and for either of recording and deleting second-type data into/from the sectors specified in the second specifying step; and an assignment updating step for updating at least one of the sector information and the block information in accordance with operations in the data updating step.
With the above construction, it is possible to record data in units of sectors or blocks. Each block includes a plurality of consecutive sectors. Accordingly, even if one file is divided and recorded into a plurality of extents, the size of the extent is larger than the size of the block at the minimum. As a result, it is possible to ensure the uninterrupted reproduction of the video data recorded on the present optical disc by preventing interruptions which are cased by occurrences of seek operations in the reproduction apparatus. Furthermore, data management in units of sectors and blocks are performed together depending on the types of data. This achieves efficient use of the recording area of the optical disc.